Hi all. I started a discussion a few weeks ago about some electrical problems, where basically under a bit of load, the dynamo isn't feeding the electrical system, even at high RPMs. The most likely solution (from this forum) was a slipping mag clutch.

However, before I pull the whole magdyno, I thought I'd first take off the dyno cover plate and see if I actually see the dynamo stop spinning. So, I did that, and noticed that the commutator/armature is still spinning good at all RPMs, even under load when I'm having these power problems. That doesn't seem right. If it's the slip clutch, the dynamo would stop spinning right? Or at least slow noticeably?

I'm trying to sort this out before pulling the whole magdyno unnecessarily. I'm thinking maybe it's the regulator instead? I'm using a 3-4 year old electrical reg from Hans Beck. Any advice?!

Craig

You can do a simple test to check the dynamo is charging with a light bulb:-

Take the F&D wires out of the end cap and replace them with two wire wound together or a small crocodile clip that will fit in both holes. This goes to the live terminal of your bulb. Then earth the bulb to your bike and start the engine. The bulb should glow and get brighter as you rev the engine.

Of course a profesional would use a meter and tell you what your actual output is ......But I'm not one of them Ron

email (option): ronpier@talk21.com

Yes...The bulb test will tell you whether you have any output...Testing with a meter will give you a better idea of whether the output is fluctuating under varying throttle openings etc...

If you do need to replace the clutch spring due to slippage you will more than likely have to replace the flat steel washer it runs against as well..That should be completely flat and unworn....Ian

email (option): ian@wright52.plus.com

I should have explained in more detail. I'm definitely getting charge, and increasing charge with increasing RPM. Checked with a meter, not a bulb. So dynamo is working well as long as there is little or no load.

The problem is, as soon as I put a large load on the system (headlamp, or horn, or both), the charge cuts out. However, even when it cuts out, the dynamo is still spinning. So I assume it's not the slip clutch then, right? That is, even though the charge cuts out, the dynamo is still spinning at the same speed, so the clutch doesn't seem to be slipping. I have no idea what would cause the dynamo to cut out though when it's still spinning, maybe regulator???

I think you will find that it is slipping, it doesn't have to slow by much to not develop enough charge. This happened on my B33 exactly the same, it only stopped when I tightened the clutch.